Contact printer



March 25, 1941.

A. W. TONDREAU CONTACT PRINTER Filed Sept. 17, 1938 4 Sheets-Sheet 2 w mw w && wmm 7 3 W, F 7 w v Z w /E A i w n L w Al N g 8 9 7 M: m mw H 5 QMy M w 5 a M 4 w 0 {W WV ATTORNEY.

INVENTOR. AL BEPT W. TONYDQEAU ATTORNEY.

4 Sheets-Sheet 3 March 25, 1941.

Patented Mar. 25, 1941 UNITED STATES CONTACT PRINTER Albert W. Tondreau,

Glendale, Calii'., assignor to Warner Bros. Pictures, Inc., New York, N.Y., a corporation of Delaware Application September 17, 1938, Serial No.230,523

12 Claims.

This invention relates to photographic printing apparatus and hasparticular reference to printing apparatus wherein a developed printingfilm and a sensitized film being printed are continu- 5 ously run incontact with each other across a printing light beam.

In contact printing, it is essential that intimate contact with minimumrelative slippage, be maintained at the printing point between theprinting film and the sensitized film being printed. This is especiallytrue when printing sound tracks, in which case even. a slight separationor relative movement between the films, i. e. .0005 inch causesdistortion of the graphically 15 produced sound modulations of the soundtrack.

Furthermore, it is essential, especially when printing sound tracks, tomaintain an even printing illumination throughout the area being printedwhile preventing any reflection of the printing beam either internallyof the films themselves or therebehind onto the sensitized film duringthe printing operations. Heretofore, when printing sound tracks from onefilm to another wherein, according to present day standards where the 25sound tracks are positioned directly adjacent one row of sprocketperforations, it has frequently been found that an unwanted 96 cyclemodulation has been introduced into the sound track being printed. Ihave discovered that this 96 cycle modulation has been due largely tothe printing light beam striking the edges of the sprocket perforationsdirectly adjacent the sound track and thereafter reflecting back ontothe sensitized film. This reflection, of course, oc- 35 curred only atpoints opposite the sprocket perforations vand thus caused fogging ofthe sound track on the sensitized films at regularly spaced areas. Whenthe sound track film thus printed was subsequently reproduced, theseregularly spaced, fogged areas of the sound track passed the reproducingpoint at the same frequency as the sprocket perforations, namely 96times per second and thus produced a 96 cycle hum. I have discoveredthat this effect is especially no- 45 ticeable where the printer lightbeam is flooded onto the film without the use of an optical systeminstead of being projected thereon. In this case, a large amount of therays of printing light strike the film at an angle, and consequentlystrike the edges of the sprocket perforations in both the printing filmand the sensitized film at an angle, causing an unwanted reflection ofsuch light onto the sensitive film to fog the same.

I Furthermore, I have discovered that when the 55 films being printedwere wrapped or guided around an arcuate surface, they were minutelyseparated at the points where the sprocket perforations occur and thatsince the sound track is in immediate proximity to the perforations, thefilm along this track was also minutely separated at spaced intervals.This, of course, gave rise to distortion in printing. This minuteseparation between the films at the sprocket perforations was probablydue to the slight burrs or raised edges formed around such perforationseither during the perforating operation or by later warping of thefilms. Also, inasmuch as a film is stiffer across the lands"intermediate the sprocket perforations than across the perforationsthemselves, the film, when wrapped around an arcuate or cylindricalsurface will assume a polygonal shape instead of a perfect arc. Thesuperposition of two of such polygonally shaped films over an arcuatesurface tends to cause the films to separate slightly along the sprockethole 2 perforations and parts adjacent thereto, including the soundtrack, thus tending to separate the films.

Furthermore, due to the fact that the films assume a polygonal shapealong the sprocket perforations as they are wrapped around an arcuatesurface, the printing light beam, as it passes through the portion ofthe printing film directly adjacent the sprocket perforations, i. e. thesound track, on its way to the sensitized film is refracted in anirregular manner by such film due to the fact that the sound trackportions of the films continually assume minutely different an gularpositions relative to the axis of the printing light beam as the filmspass thereacross, thereby tending to distort the sound track printed onthe sensitized film.

Accordingly, one object of the present invention is to obtain at theprinting point an intimate contact between the pair of films beingprinted.

According to another phase of the invention, the films are passed overan arcuate surface at the printing point and are tensioned on eitherside thereof to maintain an intimate contact between the two films onsuch surface at the printing point. A rotatable toothed drum, forming apart of such arcuate surface, is provided to drive the films past theprinting point. According to the present invention, the tension on thefilms on one side of the arcuate surface is maintained less than that onthe other side to permit the drum to drive the films thereover whilereducing the driving load on the teeth'thereof.

Another object is to facilitate adjustment of an optical system forprinting films.

Another object is to permit individual adjustment of the elements of anoptical system for a printing apparatus while permitting adjustment ofthe optical system as a whole.

Another object is to photographically form identification marks on afilm being printed simultaneously with the printing thereof from anotherfilm.

Another object is to regulate the color characteristics of a printinglight.

Another object is to ventilate a printer lamp housing while preventinglight leakage therefrom.

The manner in which the above and other objects of the present inventionare accomplished will be readily understood on reference to thefollowing specification read in conjunction with the accompanyingdrawings in which:

Fig. 1 is a side elevational view of a printing apparatus, with partsbroken away, embodying the present invention.

' Fig. 2 is a sectional plan view through the printing mechanism and istaken along the line 2 2 of Fig. 1.

Fig. 3 is a sectional view taken along the line 3-3 of Fig. 2.

Fig. 4 is a sectional, elevational view through the film drivingmechanism of the printer and is take along the line 4'-4 of Fig. 3.

Fig. 5 is a sectional view through the edge number printing attachmentand is taken along line 5-5 of Fig. 4.

Fig. 6 is an enlarged sectional view through the optical system for theprinter and is taken along the line 66 of Fig. 3.

Fig. 7 is a front view of the pad roller and.

mount therefor and is taken in the direction of the arrow I of Fig. 4.

Fig. 8 is-a sectional view showing the construction of the filter slideand is taken through the lens tube along the lines 8-8 of Fig. 6.

Referring particularly to Fig. 1 the printing machine comprises acasting I0 supported at the top of a standard I I forming the supportfor the printing machine. A printer head casting, generally indicated atI2, is secured to one side of the casting ID by bolts I3 and carries thevarious film driving and printing elements.

The printer head casting|2 comprises a bored semicylindricalprotuberance I4 forming a printing compartment housing. A vertical wallsection I5 integrally formed at one end of the housing l4 forms abearing support for the various film driving elements.

The negative or printing film I5 is supplied by a supply reel l1rotatably mounted in a manner not shown upon a standard l8 supportedfrom the printer head casting I2. The printing film l6 after passingthrough the various film driving and printing elements is reeled upon atakeup reel I9 below the casting l2 androtatably mounted in a suitablemanner on a bracket 20 extending from the printer standard II. The

positive or sensitized film 2|, on which images from film l6 are to beprinted, is supplied by a supply reel 22 rotatably mounted above theprinting mechanism by a suitable bracket (not shown) extending from thestandard l8. Film 2 I, after passing through the various film drivingand printing mechanisms is stored upon a takeup reel 23 also rotatablymounted upon bracket 20. These take-up reels I9 and 23 are driventhrough suitable slip clutches (not shown) by a continuously driven belt24.

Referring now particularly to Fig. 4 the printer film l6 after passingfrom the supply reel I1 is guided into contact with the sensitized film2|, led-from its respective supply reel. These films are then led arounda guide roller 25, around a feed or pull down sprocket 28, beingmaintained roller-33, around a guide roller 34 and is thence led intocontact with the film I6 while passing over the drum 30. It will benoted that the film 2|, on passing into engagement with the film it overthe drum 3|) converges therewith at an angle of approximately 5. Theprovision of these converging paths of films I5 and 2| as they are ledonto drum 30 permit the air therebetween to be continuously squeezed orwrung rearwardly instead of being trapped therebetween to cause aseparation of the films. This squeezing or wringing action is causedboth by the tensioning of the films I6 and 2| over the drum 30 and bythe pressure of a pad roller I35 against the two weighted roller 36,over a hold back sprocket 31 being held in engagement therewith by a padroller 38, thence over a guide roller 20 and there-' after onto theirrespective take-up reels.

The weighted roller 28 is rotatably mounted on the end of an arm 4|, theother end of which is pivotally journalled on the stationary shaft 29 ofthe roller 29. Shaft 29 is rigidly secured to the wall section I5 ofcasting I2. A weight 42 is provided on the arm 4| to cause the roller 28to exert a tensioning eifect of approximately one pound on the film I6intermediate the sprocket 25 and toothed drum 3!). The weighted roller33 is likewise mounted on an arm 43 which is pivotally mounted on astationary shaft 34 of the roller 34. Shaft 34' is also rigidly securedto the wall section I5 of casting l2. A weight 44 on the arm 43 isprovided to cause the roller 33 to exert a tension of approximately onepound and one-half on the film 2| intermediate the sprocket 26 and drum30. The weighted roller the tensioning of the films above and below thetoothed drum 30 an intimate contact between the films will be maintainedwhile passing thereover. Furthermore, due to the fact that thetensioning effect is greater on the films above the printing drum 30than below the drum, the sprocket teeth 50 of drum 30 will produce adriving effect on the films but with the tooth load thereon less thanthe tension applied to the films. That is, the leading edges of thesprocket teeth 50 will engage the leading edges of the sprocketperforations of films l6 and 2| as the films pass over the drum 30. Thismaintains the films in accurate registration with each other. For thisreason, I prefer to so adjust the film tension above and below the drum30 that a.

minimum tooth load will be maintained to reduce film wear whileproviding a sufficient amount of such tooth load to maintain accurateregistration of the films with the sprocket teeth 50. I have found thatby providing a tooth load of approximately one pound for each film, suchas results from employing the above mentioned tensioning values,satisfactory film registration is obtained.

Also, since the tension in film l6 governs only the contact between filmHi and drum 30, while the tension in film 2| governs both the contactbetween the films l6 and 2| as well as the contact between these filmsand drum 30, I prefer to employ a greater tension in the film 2| than infilm IS.

The loop in the two films I6 and 2| intermediate the drum 30 and thesprocket 31 is preferably so adjusted that the roller 36 resting thereinassumes such a position that a line passing through the axis of rotationof roller 36 and the axis of pivotal movement of arm 3'! liesperpendicular to the surface of the guide plate 35. -Further, when inthis position the guide plate 35 will be tangentially aligned at one endthereof .with the surface of the drum 30 and at the other end thereofwith the surface of the roller 36.

The two fiat guide plates 32 and 35 are suitably secured to the housingor protuberance H at the base of an opening 41 formed therein. Opening4! permits the films l6 and 2| to be led onto the drum 30.

It should be noted at this point that the rollers 29 and 34 are edgeguiding rollers having spaced flanges as at 8 and 9, respectively,thereon to engage and guide the opposite edges of the filmsagainstlateral movement as they pass onto the drum 30. Thus each filmwill be individually edge guided, there being no provision for edgeguiding of the films thereafter while in contact with each other.

Referring now to Figs, 2 and 3 the drum 3!! is formed of a sprocketmember 48 having a row of sprocket teeth 50 therearound, which member isintegrally formed on a shaft 5| rotatably mounted in a bearing member52. Bearing member 52 is secured within the bore 3|, forming theprinting compartment, by screws 53. A cylindrical flange 54 secured tothe sprocket member 48 by screws 55 forms a rotatable film support forthe picture portion of the films passing over the drum 30 whilepermitting the sound track portion of these films to overhang. Astationary ring member 55 is fitted within the bore 3| and is securedtherein by screws 56. Ring 55 has a reduced cylindrical bearing portion51 thereon of the same diameter as, and concentric with, film drum 3|]to support the overhanging portion of the films passing over the drum3!] while being spaced from the open end of the flange 54 of drum 30 byan amount substantially equal to the width of the sound track.Preferably, however, the inner edge of the bearing portion 51 of ring 55extends approximately .002 over the edges of the sprocket perforationsdirectly adjacent the sound track to prevent the printing light beamfrom striking such edges. It will be noted that the adjacent edges ofthe fiange 54 and ring 55 are chamfered as at 58. This provision forlaterally supporting the films throughout the entire width thereofexcept the sound track portions, eliminates any tendency of the film tobow transversely and therefore aids in maintaining an intimate contactbetween the films themselves and between the films and the drum 30 andbearing portion 51 of ring 55 at the printing point.

Describing now the drive for the sprockets 26 and 31 and drum 30, ahelical gear 60 (Figs. 2, 3 and 4) is secured to the shaft 5| of drum3') and is driven by a similar small gear 6| (Fig. 4) r eshing therewithand secured in driving relation to a pulley 62 over which thecontinuously driven belt 24 is engaged. Gear 6| alsomeshes with a gear59 aflixed to shaft 31' of sprocket 31. A gear 63 secured to the shaft26' of sprocket 26 is driven from the gear 50 by an intermediate idlergear 54. The shafts of gears 59, 6|, 63 and 54 are all suitablyjournalled in bearings formed in wall section I5.

Referring to Figs. 2, 3 and 6, I will now describe the optical systemfor projecting a printing light beam onto the sound track portions ofthe films l6 and 2| while passing in contact in an arcuate path over thedrum 30 and bearing portion 51 of ring 55 The optical system comprisesgenerally a lamp house 66 containing a printing lamp 61, a lens mountgenerally indicated at 68 having a prism 69 at the forward end thereoffor deflecting the printing beam of light into the sound track portionof the films 6 and 2| intermediate the adjacent edges of the drum 3!]and ring 55.

As shown in Fig. 6, the mount 68 comprises a cylindrical tube I0. A slitmember 7| having a horizontally extending slit 12 formed therein isthreadably secured in the rear end of the tube 10, Also threadablysecured in this end of tube 10 is the mount for a condenser lens 13. Theopposite end of tube 10 is securely fitted within the slide block 74,having a vertically extending slide aperture 15 extending therethrough.A tapered objective-tube 16, co-axial with tube 10, is threadablymounted in the opposite end of the block 74 and carries at its forwardend a pair of objective lenses 11. The size of the slit l2 and themagnification of the objective lenses ll are such that a horizontal slitof light approximately .009" high and .010" long is focussed upon thefilms at the point P (Fig. 4) The length of this slit of light istherefore sufiicient to extend entirely across the gap or openingbetween the adjacentedges of the drum 30 and ring 55. The right angleprism 69 is mounted in a prism block 19 having a bore therein fittedover the forward end of the tube 16. A set screw 79 threadably mountedwithin the block 70 permits the prism 69 and block 19 to be locked inany adjusted position about the tube 16.

As shown in Figs. 2 and 3 the tube H1 is slidably and rotatably mountedin a bushing ll secured to and extending through an end plate or covermember 18. End plate 18 is secured across the bore 3| provided in thehousing l4 by bolts 89 and 8|. Bolts 80 and 8| extend through elongatedhorizontally extending slots 82 and 83, respectively, formed in theplate 18, permitting transverse adjustment of the plate 18 and mount 68,carried thereby, in a horizontal direction. A set screw 84, threadablymounted in the bushing 11, permits rotatable as well as longitudinaladjustment of the tube 10 and the lamp house 66 carried thereby.

Referring now to Figs. 3, 6 and 8, a filter slide, generally indicatedat 85, is slidably mounted within the aperture ii in block 74. Filterslide 85 comprises a channel shaped member 85 having three I spacedapertures 81, and 80 formed therein, any one of which is adapted to bepositioned, on movement; of slide 85, in the path of light through thetube I0. The upper aperture 87 is in the form of. a horizontal slit toreduce the amount of light passing therethrough, the other two apertures88 and 89 being circular. A pair of fiat glass blocks 90 and SI having dfier- SI to retain the same in place.

transmission of light through the blocks 90 and 9I, respectively. Theaperture 93 is in the formof a horizontal slot to reduce the amount oflight passing therethrough. These filter blocks 90 and 9t may have anydesired color absorbing characteristics. For example, block 90 passesonly ultra violet light and is inserted in the path ofthe printing lightbeam through the tube I0 whenever ultra violet printing is to beemployed, while the block 9I permits only the blue component of theprinting light to pass therethrough and is insert- .ed in the printinglight beam whenever fine grain film is to be printed. The slide ismanipulated from the exterior of the printer housing Ml by means of arod 95 loosely mounted on a transversely extending pin 96 secured in theopposite legs of the channel member 86. Rod 95 extends It and thenceextends loosely through a block 91 (Fig. 3) secured in a suitable manneron top of the housing It. A series of three circumferential slots 98, 99and I00 are formed at spaced intervals along the rod 95 and are adaptedto be selectively engaged by a plunger member I00 slidable transverselyin the block 91 and urged against the rod 95 by a springifiI. When oneor the other filter blocks and BI, or the aperture 8! is to be movedinto position in the printing light beam, the plunger m0 is retractedfrom engagement with one of the slots 98, 99 or I00, and the rod ismoved vertically until the correct aperture or filter block ispositioned in the tube 70. The plunger I00 is then allowed to engage thecorresponding slot 98, 99 or I00 to hold the filter slide 85 in itscorrectly adjusted position. A considerable amount of loose play isprovided between the rod 95 and the aperture in the block 97 throughwhich it slides, whereby the tube l0 may be adjusted longitudinally tocorrectly align the optical system with the sound track portions of thefilms being printed. Also, a considerable amount of play is providedbetween the lower end of the rod 05 and the pin 90, on which it ispivotally secured, whereby the tube I0 may be transversely and rotatablyadjusted slight amounts to correctly align and focus the optical systemon the films IB- and 2t. It will be understood, of course, thattransverse adjustment of tube I0 will cause a change in the focus of theprojected beam of light passing 'therethrough due to the right angledeflection of the beam by the prism 69.

Aswill be noted in Figs. 1, 2 and 3 the printer lamp'housing 06comprises a vertically extending cylindrical shell N35 having a crescentshapedsupporting member I05 surrounding the same and secured thereto byscrews W6. A bushing I01 extending through both the member I 06 andshell l05 is'adjust'ably fitted over the outer end ofthe tube IIJ-andhas a set screw 38 threaded therein whereby the lamp house 66 issupported by tube- I0 and may be adjusted longitudinally and rotatablyabout the tube I0.

The base of the lamp house 66 comprises a cylindrical end cover memberI09 fitted with the shell I05 and secured thereto by screws II'0. A pairof spaced circumferentially extending channels III and H2 are formedaround the member I09. A series of spaced vent holes I13 exte'nd betweenthe channel III and the interior ent color filtering values aremountedin the of the housing 66. A second series of vent holes channel member88 over the apertures 88 and 89, respectively. A cover plate 92 ismounted on the member 86 by screws 92 over the blocks 90 and A'pertures93 and 94 are provided in the cover plate 92 to permit tures H4. Thelabyrinth air venting passage I I4 extend between the channels III andH2 and are staggered in relation to the other holes I I3 as shown inFig. 2. A third series of vent holes II5 are formed in the shell I05 andcommunicate with the channel I I2 in staggered relation to the aperthusformed permits air to pass into the lamp housing 66 while preventingleakage of printing light therefrom. The upper end of the shell I05 isclosed by a cover member I I6 having a tubular extension I I! formedcentrally thereof and defining an opening. A flexible hose H8 is fittedover the extension I and is connected to a suitable vacuum pump (notshown) to draw cooling air through the lamp housing 66 from thelabyrinth passage at the base thereof to cool lamp 61.

Lamp 61 is mounted in a socket II 8 fitted in an opening I20 formed in alamp supporting pla-te I2I which is secured to the base member I09 byscrews I22. A set screw I23 threadably mounted in the plate I2I permitsvertical and rotatable adjustment of the socket II9 to correctly alignthe filament tiI' of lamp 61 with the optical system in the mount 68. Inlieu of a single filament lamp as illustrated, I may employ amultifilament lamp. Lamp 61 is connected to a suitable source of supplyby a conductor I10 and has a rheostat generally indicated at Ill(Fig. 1) in circuit therewith. Rheostat lII is suitably secured to thecasting lI within easy reach of the operator of the printing machine.

From the foregoing it will be seen that the entire optical system,including the printing lamp 5?, for printing the sound tracks of thefilms I6 and 2! is supported by the tube I0, carried by the end platei8. Thus, the provision for lateral adjustment of the endplate I8 aswell as the provision for longitudinal and rotatable adjustment of thetube 10 permits an adjustment of the entire optical system as a whole.Also, the provision of the set screw I9 in the prism mount I9 as well asthe set screws I23 in the lamp housing plate iii and the set screw I08in the lamp supporting bushing I07, and movable filter slide 85, permitsadjustment of the various elements of the optical .or light projectingsystem individually.

Referring now to Figs. 2, 4 and 6, I will now describe the means forexposing identification marks on a sensitized film whereby to identifythe particular printer in which such film was printed. Agroove or notchI25 (Fig. 6) is formed at one point within the printing drum 30. A smallpassage E25 communicates this groove I25 with a point on thecircumference of the drum 30 intermediate two of the sprocket teeth 50.This passage E26 is adapted to transmit light from a small lamp i2? tothe films I6 and 2| at each revolution of the drum 30. Lamp I2! ismounted in a housing I28 secured on a bracket I29 supported on thefilter slide block it by screws Hill. A light passage I3l is formed atthe 'front of the housing I128 to direct a pencil or beam of light fromthe lamp in toward the circular path of movement of the passage I26. Anarcuately shaped light shield I 62 (Figs. 4 and 6) is secured .to thelamp housing I26 to prevent refiection of light from the lamp I21 ontothe sound track portion of the films being printed. The edge I32 ofshield I32 lies closely adjacent the inner surface of the drum so thatany light passing therebetween is not in line with the films beingprinted. Current is supplied to the lamp I21 through a conductor I 34passing through an aperture in the cover plate 16 and connected to asuitable source of current supply. It will be seen, therefore, that whenthe passage I26 passes beneath the line of light from the lamp I21, oneach revolution of the drum 30, light will be transmitted to the filmsI6 and 2I. Since, according to present practice, the space intermediatethe sprocket perforations is generally left transparent, the light willpass through the negative or printing film I6 and thus fog or expose anidentification mark on the film 2| at a point intermediate two of thesprocket teeth 60. By arranging any number of passages I26 or by varyingthe shape of such passages, diflerent identification marks may beprovided for different printer machines.

To further obtain an intimate contact between the two films I6 and 2I atthe printing point, a pad roller I36 (Figs. 2, 4, 6 and 7) is provided.Roller I36 engages the films at a point directly opposite the printingpoint P and straddles both the drum 30 and the bearing portion 61 ofstationary ring 55. A self-aligning mount, generally indicated at I 31,i provided to resiliently urge the roller I36 against the films incontact. Mount I 31 comprises a stirrup I36 in which the shaft of rollerI36 i rotatably mounted. Stirrup I38 has a vertically extending bearingformed therein which is pivotally fitted'over a bearing portion I40formed at the bottom of a rod I H. Rod I4I extends through an apertureformed in a swivel block I42 and 1s adjustably secured therein by a setscrew I43 permitting vertical adjustment of the roller I 36. Block I42has a horizontally extending bearing stud I44 thereon journalled in abearing block I45 which is secured as by screws I46 to a gate memberI46. Gate member I46 is pivotally mounted upon a stationary bearing studI41 projecting from the wall I5 permitting movement of the roller mountI31 toward and away from the drum 30 for film threading purposes. RollerI36 is resiliently urged against the films I6 and 2i by a tensionspring, I48 extending between the upper end of rod HI and a piece I49secured to the pad member I46. A stop pin I50 is threadably mounted inthe piece I49 for longitudinal adjustment thereof. The head of pin I50is adapted to engage the rod Hi to limit the inward movement of theroller I36. Pad member I46 is limited in its inward movement by a setscrew I5I (Fig. 2) and is adapted to be held in that position by aspring I63 (Fig. 4). Spring I53 surrounds a plunger rod mounted at theupper end thereof to a dependent lug I55 integrally formed on the padmember I46 below the stud I41. Spring I54 engages at one end thereof aflange I56 formed on the rod I 54, and at the other end thereof a sleeveI 51 through which the rod I54 is s'lidable. Sleeve I 51 is seated upona semi-cylindrical projection I66 forming a bearing for a shaft I59.Projection I56 also has an aperture I62 in which the rod I64 is looselymounted to slide therethrough. Shaft I56 has a radially extending holeI60 therein which, when aligned with the rod I54, permits the same to'various metallic surfaces behind the films.

I54 pivotally project therethrough. Shaft I56 is adapted to be rotatedby a handle I6I (Fig. 1) to align the hole I60 with the rod I64, thuspermitting the rod I64 to extend into the hole I66 for the purpose ofmoving the gate member I46 into threading position. Spring I63 acts as asnapover spring to hold the gate member I46 in an open position awayfrom the opening 41 in housing I4 when the gate member I46 is movedcounterclockwise approximately A switch (not shown) in circuit with theprinting lamp I61 is actuated by the shaft I69. When the shaft I66 isrotated to align the hole I60 with the plunger rod I64, this switch willbe opened to extinguish the printer lamp. Thus, this switch forms asafety feature, preventing the lamp from being illuminated until thegate member I 46 is closed.

The edge printing device comprises a small box shaped lamp compartmentI63 (Figs. 4 and 5) secured to the rear of the lower guide plate 35 byscrews I64. A printing lamp I66 supported in a socket I66 within thecompartment I63 is adapted to project a beam of light through a smallprinting aperture I66 formed co-extensively through the forward wall ofthe compartment I63 and the guide plate 36. This passage I66 is directlyin hers along the film I6 to permit such numbers to be printed on thesensitive film 2i. A suitable switch (not shown) is provided in thecircuit of lamp I66 to open such circuit when it is not desired to printedge numbers. A mask I61 is integrally mounted on a pin I66 journalledin a bearing lug I66 projecting from the wall of compartment I63 and,when moved into one position, intercepts the line of light passingthrough the passage I66 and the films I6 and 2I to prevent the same fromfogging the sensitized film 2I after passing therethrough due toreflection from Mask I61 is rotatable into an out-of-the-way position topermit threading the films in the machine,

Certain features disclosed herein are disclosed and claimed in myco-pending application 249,956, filed January 9, 1939, for Film printingapparatus and in my U, S. Patent 2,199,764, granted May 7, 1940, forFilm marking apparatus."

I claim: 1. In a film printing apparatus, a rotaiable film supportingmember having a cylindrical flange thereon, said flange being adapted tosupport a film with a portion of said film overhanging said flange andsaid flange having an aperture extending therethrough, a light source.an opt cal system for projecting a beam of light from said light sourceonto said overhanging portion of said film on said flange, a mount forsaid optical system, a second light source, means on sad mount forsupporting said second llQhi source within said flange. said lightsource being d rected toward the path of movement of said aperture, anda shielding member intermediate said second light source and theoverhanging portion'of said film.

2. Printing apparatus comprising the combination of a hollow drumadapted to support films in printing relation, said drum having a closedend and an open end and means for rotatably supporting said drum, a setof sprocket teeth around said drum adjacent the closed end thereof, anexposure aperture comprising a light passage extending from the interiorto the exterior of said drum between adjacent ones of said sprocketteeth, means providing a light beam therefor, means'providing a lightbeam for print ing sound track from one to the other of the filmsoverhanging the edge of said drum and means for shielding one of saidlight beams from the other.

3. Printing apparatus comprising a hollow drum having a flange adaptedto support a light sensitive film and another film in contact inprinting relation beyond said flange, means associated with said drumfor printing said light sensitive film, an aperture through said drum,and means inside of said flange and associated with said aperture forexposing an identification mark on said light sensitive "film outsidethe printing area beyond said flange.

4. A film printing apparatus comprising a rotatable open drum definingone side of the printing area and adapted to guide a pair of films incontact thereover with the printing area and one edge of said filmsoverhanging said drum, a hollow film guiding member concentric with andspaced from said drum for defining the other side of the printing areaand for guiding the overhanging edges of said films, means projectingthrough said hollow film guiding member for projecting a beam of lightsubstantially radially onto said films intermediate said drum and saidhollow film guiding member at a printing point, and a pad memberengaging said films on said drum and on said film guiding member at saidprinting point.

5. Film printing apparatus comprising the combination of a printerhousing having a cylindrical bore therethrough, a rotatable film drumadapted to support a pair of superposed films thereover with one edge ofsaid films overhanging said drum, means in said bore for rotatablysupporting said drum, a supporting member concentric with said film drumfor supporting the overhanging edge of said films, means for supportingsaid supporting member in said bore, a cover member for one end of saidbore, an optical system at least partly within said bore and adapted toproject a beam of light onto said films intermediate said drum and saidsupporting member, means on said cover member for supporting saidoptical system, and means whereby said cover member may be adjustedtransversely of said bore to focus said optical system.

6. A film printing apparatus comprising 9. casing, a rotatable film drumin said casing adapted to support a pair of superposed films thereoverin printing relation, means in said casing for rotatably supporting saiddrum, said casing having an opening therein, a cover member for saidopening, an optical system for projecting a beam of light onto saidfilms on said drum, a mount for said optical system, means on said covermember for supporting said mount, said mount having an openingtherethrouglna filterslide in said opening, and actuating meansextending through said casing for manipulating said filter slide.

'7. A printing apparatus comprising a casing having a cylindrical boretherein, a film drum in said bore adapted to support a pair of films incontact thereover with a portion of said films overhanging said drum,bearing means in said bore at one end thereof for rotatably supportingsaid drum, a stationary cylindrical member in said bore adapted,- tosupport the overhanging portions of said films, said stationarysupporting member being spaced from said drum to define a sound trackprinting opening, a cover member for the other end of said bore,-anoptical system adapted to project a slit of light and arrangedsubstantially co-asial with said drum, a light defiector for deflectinga beam of light from said optical system onto the sound track portion orsaid films, a mount for saidoptical system and said deflector, saidmount extending through said cover member, means on said cover memberfor securing said mount thereto, a lamp house, means for securing saidlamp house on said mount, and a lamp in said lamp house for projectinglight through said optical system.

8. Printing apparatus according to claim '7 comprising means wherebysaid mount may be adjusted longitudinally through said cover memher.

9. Film printing apparatus comprising a film drum having sprocket teeththereon, feed sprocket means for leading films in printing relation ontosaid drum, means for printing from one of said films to the other atsaid drum, takeup sprocket means for leading said films oil of saiddrum, a synchronous power drive coupled to said drum, said feed sprocketmeans and said take-up sprocket means, means for guiding said films oversaid drum in an arc, means for tensioning the portion of said filmsintermediate said drum and said feed sprocket means, and simultaneouslyoperative means for tensioning the portion of said films intermediatesaid drum and said take-up sprocket means to a lesser degree than saidfirst mentioned tensioning means.

10. Film printing apparatus according to claim 9 wherein the tension inthe outer of said filins at said drum is greater than the tension in theinner of said films at said drum.

11. Printing apparatus comprising a printing drum having sprocket teeth,means for traversing a pair of films in printing relation over saiddrum, a synchronous power drive coupled to said drum and to saidtraversing means, means for printing from one of said films to the otherat said drum, and film tensioning means at opposite sides of said drumand intermediate said traversing means and said drum for simultaneouslytensioning said films, said film tensioning means at one side 01 saiddrum being more eifective than the film tensioning means at the otherside thereof whereby one side oi the sprocket holes of said films iscaused to drag against the sprocket teeth on said drum.

12. Film printing apparatus comprising a printing drum having sprocketteeth, a feed sprocket and take-up sprocket at opposite sides of saiddrum for traversing a pair of films in printing relation over said drum,means for printing from one of said films to the other at said drum,means for synchronously driving said sprockets and said drum at the sameperipheral speed, film tensioning means for both of said filmsintermediate said feed sprocket and said drum and intermediate saidtake-up sprocket and said drum for simultaneously tensioning said filmswherein said film tensioning means comprises means for tensioning saidfilms a greater amount at one side of said drum than at the other.

ALBERT W. TONDREAU.

